How could there be different explanation for the same event in history?

By studying the details and the different opinions of each of the historians

Two people might witness the event but not necessarily have the same point of view. Some people might be experts in a certain area, like warfare or being a ship's captain, and therefore might be more qualified to say what actually happened than someone without that expertise. Both people could be telling the truth as they saw and heard it, but the actual events might be different. In addition, some people might be biased, and their personal opinions of an event could influence their account.

Explanation:

the california missions began in the late 18th century as an effort to convert native americans to catholicism and expand european territory. there were 21 missions in all, lasting from 1769 until about 1833.   the missions were built by the spanish starting in 1769 in order to “colonize” the territory of alta california. so the missions were important because they were the means of settling california. it also wanted to keep other european countries out of alta california. building settlements along the coast would them meet these goals. missionaries wanted to convert the indians to the roman catholic faith. california indians did much of the work to build missions.

polling is a process and the outcome is not involved in the process itself.

the outcome, which is an unfavorable rating for a particular candidate is not affected by the mechanical process of polling.

it rather depends on the number of people voting in favor of the candidate.

this is an outcome of people's preferences.